In a 5 gallon pot, I would just water around the plant. You do not want to see runoff unless you have really porous soil, until the plant is large enough to deal with it. I would use about 1/2 gallon per watering depending on medium, and then water again as the soil dries out, every 3 days is what I average, but I have large plants usually. You won't need that amount for now.